The purpose of this project is to develop and apply improved methods of myocardial perfusion quantitation, myocardial flow reserve and wall dynamics for the evaluation of the effects of coronary artery disease. The protocols emphasize flow quantitation using PET with applications to detection of dysfunctional reversibility and to quantitation of coronary perfusion reserve. A major hypothesis is that quantitative PET perfusion is able to show the likelihood that dysfunctional myocardial segments will recover following revascularization procedures and that perfusion quantitation is superior to fluorodeoxyglucose accumulation patterns or other contemporary non-invasive approached being used to assess viability. Forty patients who are to receive by-pass surgery will be studied. A new perfusion tracer using the 122Xe/122I generator could replace the need for an on site cyclotron and make Pet perfusion studies markedly more economical and practical in view of the new sources for 122Xe. The technological improvements in MRI could challenge PET methods for evaluation of ischemic heart disease and perfusion reserve thus these MRI methods will be compared to the best of the PET methods in years 4 and 5. Four cardiologists (three with the nuclear medicine specialty) and a cardiac radiologist have been included in addition to the medical scientist developing needed technology.